Wedderburn–Etherington number

sequence of numbers counting certain kinds of binary trees

Wikidata entity: Q2068748

P2534	defining formula	Math	$a_{2 n - 1} = \sum_{i = 1}^{n - 1} a_{i} a_{2 n - i - 1}; a_{2 n} = \frac{a_{n} (a_{n} + 1)}{2} + \sum_{i = 1}^{n - 1} a_{i} a_{2 n - i}$	???
P31	instance of	...	Q2297602 (integer sequence)	integer sequence
P6104	maintained by WikiProject	...	Q8487137 (WikiProject Mathematics)	WikiProject Mathematics
P279	subclass of	...	Q28920052 (non-negative integer)	non-negative integer

External Ids

P646	Freebase ID	/m/03vlsc
P829	OEIS ID	A001190

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